CVE-2026-74726
HighCVSS 7.3Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
In the Linux kernel bonding driver (ALB mode), bond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and takes RTNL via rtnl_trylock() before undoing promiscuity on the active slave. In that window the active slave can change, leading to a null-pointer dereference (kernel panic) or an underflow of the promiscuity counter, leaving the interface in IFF_PROMISC.
Risk Assessment
The vulnerability can cause a kernel panic or permanently enable promiscuous mode on a network interface, increasing the risk of traffic interception and network integrity issues. However, exploitation requires local access and the ability to modify bonding interface configuration.
Recommendation
Immediately update the Linux kernel to a version containing the fix (re-check primary_is_promisc after acquiring RTNL). If updating is not possible, restrict access to bonding interface management to trusted administrators only.
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In the Linux kernel XFS filesystem, during directory tree repair, a self-referential directory may be detected. In such a case, the repair code attempts to lock the same inode twice (double iolock/ilock), leading to a deadlock. The fix detects this corner case and handles it appropriately.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor bond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and takes RTNL via rtnl_trylock() before undoing the promiscuity it set on the active slave. In that window the active slave can change under RTNL (RTM_DELLINK -> __bond_release_one() -> bond_alb_handle_active_change()), which already drops the promiscuity and clears primary_is_promisc. The monitor still acts on the stale decision: if the slave was removed with no failover, curr_active_slave is now NULL and the deref faults; if it failed over, the stale dev_set_promiscuity(-1) underflows the new slave's promiscuity counter and pins it in IFF_PROMISC. Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: b42 bond_alb_monitor RIP: 0010:bond_alb_monitor (drivers/net/bonding/bond_alb.c:1600) process_one_work (kernel/workqueue.c:3322) worker_thread (kernel/workqueue.c:3486) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) Kernel panic - not syncing: Fatal exception Re-check primary_is_promisc (and curr_active_slave) after taking RTNL so the monitor only undoes an increment it still owns. The other bonding monitors already re-read state under RTNL in their commit phase (bond_miimon_commit/bond_ab_arp_commit); bond_alb_monitor() was the only one acting on the pre-trylock decision.